Topical nitric oxide systems and methods of use thereof

ABSTRACT

The present invention generally relates to compositions and methods for transdermal drug delivery. The compositions can be used in a variety of applications, including treating erectile dysfunction or sexual dysfunction, treating wounds, or causing or promoting hair growth. For example, in one aspect, the present invention is generally directed to compositions for delivery of nitric oxide, transdermally and/or to a mucosal surface. The composition may include nitric oxide. The nitric oxide may be present within a first phase comprising a lecithin, such as phosphatidylcholine. In certain embodiments, the lecithin is present in liposomes, micelles, or other vesicles containing nitric oxide. The composition can take the form of a gel, a cream, a lotion, an ointment, a solution, a solid “stick,” etc., that can be rubbed or sprayed onto the skin, e.g., onto the penis, vulva, or other suitable portion of the skin. The composition can also be applied to a mucosal surface in some instances. In some embodiments, a composition comprising nitric oxide is unexpectedly stable and can be stored long-term. Thus, for example, a composition of the invention may exhibit a long shelf life, with little loss or reaction of nitric oxide. This may be particularly useful for certain applications such as consumer products, including those described herein. Other aspects of the present invention are generally directed to methods of making or using such compositions, methods of promoting such compositions, kits including such compositions, or the like.

RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. §371 of International Patent Application Serial No. PCT/US2012/000151, filed Mar. 17, 2012, entitled “Topical Nitric Oxide Systems,” by Nicholas V. Perricone, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/453,836, filed Mar. 17, 2011, entitled “Topical Nitric Oxide Systems,” by Nicholas V. Perricone, each of which is incorporated herein by reference.

FIELD OF INVENTION

The present invention generally relates to compositions and methods for transdermal drug delivery.

BACKGROUND

Topical drug delivery systems are known. These systems deliver drugs or other therapeutic agents, or other desired substances transdermally, and may be designed to act locally at the point of application, or to act systemically once entering the body's blood circulation. In these systems, delivery may be achieved by techniques such as direct topical application of a substance or drug in the form of an ointment or the like, or by adhesion of a patch with a reservoir or the like that holds the drug (or other substance) and releases it to the skin in a time-controlled fashion.

Topical delivery systems for substances such as drugs, pain relieving compounds, vitamins, and skin improving compounds have been in use for a number of years. Transdermal delivery systems using creams have been developed for use with analgesics and skin refining compounds. However, these delivery systems do not work effectively for all compounds.

SUMMARY

The present invention generally relates to compositions and methods for transdermal drug delivery. The compositions can be used in a variety of applications. For example, in some embodiments, transdermal systems and methods are provided for use in treating erectile dysfunction or sexual dysfunction. In other embodiments, transdermal systems and methods are provided for use in treating wounds. In still other embodiments, transdermal systems and methods are provided for use in causing or promoting hair growth. The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.

In some embodiments, aspects of the invention relate to methods and compositions for delivering nitric oxide transdermally. In one aspect, the present invention is generally directed to compositions for transdermal delivery that include a lecithin such as phosphatidylcholine that can contain or “trap” nitric oxide. The phosphatidylcholine or lecithin may be contained within a second phase that causes the phosphatidylcholine or lecithin to form vesicles, e.g., micelles or liposomes. Compositions such as these can be used for various applications, for example, to treat sexual dysfunction. For example, in one embodiment, a composition can be applied to the genital region, e.g., perineal and/or other genital region of a subject.

The present invention relates, in another aspect, to a composition for transdermal delivery of nitric oxide that comprises a lecithin (e.g., phosphatidylcholine) component entrapping nitric oxide, wherein the lecithin component stabilizes the nitric oxide at room temperature, at refrigerator temperature (e.g., 4° C.), or at or lower than 80° C., for extended period of storage. The composition may further comprise one or more adjunct ingredients.

In another aspect, the present invention relates to a method for treating various diseases that comprises applying to skin a composition comprising an effective amount of nitric oxide and a phase having a lecithin (e.g., phosphatidylcholine) component entrapping the nitric oxide.

In some embodiments, aspects of the invention relate to a method for treating a sexual disorder or dysfunction, by contacting a genital region of a subject with a composition comprising an emulsion having a first phase comprising nitric oxide and lecithin, and a second phase comprising an emulsifier, wherein the lecithin is present at at least about 0.25% by weight of the composition, and wherein the first phase comprises no more than about 250 ppm of water by weight of the composition.

In some embodiments, the genital region is a perineal region. In some embodiments, the genital region is a penile surface region. In some embodiments, the genital region is a vaginal surface region.

In some embodiments, the first phase forms discrete vesicles contained within the second phase. For example, the first phase can form liposomes contained within the second phase. In some embodiments, the first phase forms multilamellar liposomes contained within the second phase. In some embodiments, the first phase forms a liquid crystal.

In some embodiments, the first phase comprises no more than about 100 ppm of water by weight of the composition.

In some embodiments, the nitric oxide is present at least about 0.5% by weight of the composition. In other cases, the nitric oxide may be present at a concentration of between about 400 mg/kg and about 1000 mg/kg, and in some cases, between about 500 mg/kg and about 800 mg/kg.

In some embodiments, at least some of the nitric oxide is present within the first phase as a gas. In some embodiments, at least some of the nitric oxide is present within the first phase bound to lecithin. In some embodiments, at least some of the nitric oxide is present within the first phase bound to phosphatidylcholine.

In some embodiments, the lecithin is present at least about 0.5% by weight. In some embodiments, the lecithin is present at least about 1% by weight. In some embodiments, the lecithin is present at least about 30% by weight. In some embodiments, the lecithin is present at least about 60% by weight.

In some embodiments, the lecithin comprises a phosphatidylcholine. In some embodiments, at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising a stearic diglyceride linked to a choline ester of a phosphoric acid. In some embodiments, at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising a palmitic diglyceride linked to a choline ester of a phosphoric acid. In some embodiments, at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising an oleic diglyceride linked to a choline ester of a phosphoric acid. In some embodiments, at least some of the phosphatidylcholine comprises a polyenylphosphatidylcholine. In some embodiments, the polyenylphosphatidylcholine comprises linoleic acid. In some embodiments, the polyenylphosphatidylcholine comprises dilinoleoylphosphatidylcholine. In some embodiments, at least about 30 wt % of the phosphatidylcholine is a polyenylphosphatidylcholine.

In some embodiments, the first phase further comprises a transdermal penetration enhancer. In some embodiments, the transdermal penetration enhancer is present at least about 5% by weight of the composition.

In some embodiments, the first phase comprises a fatty acid ester. In some embodiments, the first phase comprises ascorbate palmitate. In some embodiments, the first phase comprises isopropyl palmitate. In some embodiments, the first phase further comprises 1,3-dimethyl-2-imidazolidinone.

In some embodiments, the second phase further comprises 1,2-propanediol. In some embodiments, the second phase further comprises a polyglycol. In some embodiments, the polyglycol comprises polyethylene glycol.

In some embodiments, the composition is a gel. In some embodiments, the composition is a cream. In some embodiments, the composition is substantially transparent.

In some embodiments, the composition has a viscosity of at least about 20,000 cP. In some embodiments, the composition has a viscosity of at least about 50,000 cP.

In yet another aspect, the present invention encompasses methods of making one or more of the embodiments described herein.

In some embodiments, a lipid composition can be loaded with nitric oxide by passing nitric oxide gas through the lipid composition under conditions wherein the lipid is in a fluid state. In some embodiments, nitric oxide gas is bubbled through a lipid that is in a fluid state. In some embodiments, nitric oxide gas is bubbled for about 5 hours or less, for example about 4-5 hours, about 3-4 hours, about 2-3 hours, about 1-2 hours, about 30-60 minutes, about 15-30 minutes, or about 5-15 minutes.

In another aspect, the present invention is generally directed to a method for treating diseases, e.g., by applying to skin a composition comprising an effective amount of nitric oxide and a carrier having a phosphatidylcholine component entrapping the nitric oxide.

In still another aspect, the present invention is generally directed to a method comprising contacting a genital region of a subject with a composition comprising an emulsion comprising a first phase comprising nitric oxide and lecithin, and a second phase comprising an emulsifier. In some cases, the lecithin is present at least about 0.25% by weight of the composition. In certain embodiments, the first phase comprises no more than about 250 ppm of water by weight of the composition.

The present invention, according to yet another aspect, is generally directed to a method comprising contacting a wound on the skin of a subject with a composition comprising an emulsion comprising a first phase comprising nitric oxide and lecithin, and a second phase comprising an emulsifier. In some instances, the lecithin is present at least about 0.25% by weight of the composition. In certain embodiments, the first phase comprises no more than about 250 ppm of water by weight of the composition.

According to still another aspect, the present invention is generally directed to a method comprising contacting the skin of a subject, at a location where hair growth is desired, with a composition comprising an emulsion comprising a first phase comprising nitric oxide and lecithin, and a second phase comprising an emulsifier. In accordance with certain embodiments, the lecithin is present at least about 0.25% by weight of the composition. In some cases, the first phase comprises no more than about 250 ppm of water by weight of the composition.

Yet another aspect of the present invention is generally directed to a method of formulating a topical nitric oxide composition. For example, in some embodiments, the method comprises acts of mixing a polyglycol and a phosphatidylcholine to form a phosphatidylcholine solution, and delivering nitric oxide into the phosphatidylcholine solution.

Another aspect of the present invention is generally directed to a composition for transdermal delivery of nitric oxide. In one set of embodiments, the composition comprises a phosphatidylcholine carrier entrapping nitric oxide. In some cases, the phosphatidylcholine carrier stabilizes the nitric oxide at a temperature at or lower than 80° C.

In another set of embodiments, the composition comprises an emulsion comprising a first phase comprising nitric oxide and lecithin, and a second phase comprising an emulsifier. In some cases, the lecithin is present at at least about 0.25% by weight of the composition. In certain embodiments, the first phase comprises no more than about 250 ppm of water by weight of the composition.

According to another set of embodiments, the composition comprises an emulsion comprising a first phase comprising a gas and lecithin, and a second phase comprising an emulsifier. The lecithin may be present at at least about 0.25% by weight of the composition, in some instances. In various embodiments, the gas is present at least about 0.5% by weight of the composition. In addition, the first phase comprises no more than about 250 ppm of water by weight of the composition in some cases.

The composition, in yet another set of embodiments, comprises a first phase contained within a second phase comprising a fatty acid ester. In certain cases, the first phase comprises nitric oxide and phosphatidylcholine at least about 0.25% by weight of the composition.

Still another set of embodiments is generally directed to a composition comprising a first phase and a second phase substantially immiscible in the first phase. The first phase may comprise nitric oxide and phosphatidylcholine in certain embodiments.

In another set of embodiments, the composition is generally directed to a gel or a cream comprising nitric oxide. In some instances, the gel comprises no more than about 250 ppm of water. In some embodiments, the first and second phases of a composition each comprise no more than about 250 ppm of water. In some embodiments, one or more of the materials used to prepare a nitric oxide containing composition each comprise no more than about 250 ppm of water. In some embodiments, a nitric oxide containing composition prepared as described herein comprises no more than 250 ppm of water.

In still another aspect, the present invention encompasses methods of using one or more of the embodiments described herein.

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and/or inconsistent disclosure with respect to each other, then the document having the later effective date shall control.

DETAILED DESCRIPTION

The present invention generally relates to compositions and methods for transdermal drug delivery. The compositions can be used in a variety of applications, including treating erectile dysfunction or sexual dysfunction, treating wounds, or causing or promoting hair growth. For example, in one aspect, the present invention is generally directed to compositions for delivery of nitric oxide, transdermally and/or to a mucosal surface. The composition may include nitric oxide. The nitric oxide may be present within a first phase comprising a lecithin, such as phosphatidylcholine. In certain embodiments, the lecithin is present in liposomes, micelles, or other vesicles containing nitric oxide. The composition can take the form of a gel, a cream, a lotion, an ointment, a solution, a solid “stick,” etc., that can be rubbed or sprayed onto the skin, e.g., onto the penis, vulva, or other suitable portion of the skin. The composition can also be applied to a mucosal surface in some instances. In some embodiments, a composition comprising nitric oxide is unexpectedly stable and can be stored long-term. Thus, for example, a composition of the invention may exhibit a long shelf life, with little loss or reaction of nitric oxide. This may be particularly useful for certain applications such as consumer products, including those described herein. Other aspects of the present invention are generally directed to methods of making or using such compositions, methods of promoting such compositions, kits including such compositions, or the like.

Unlike prior art that employs only nitric oxide donors as nitric oxide sources, in certain embodiments of the present invention, nitric oxide gas itself is entrapped or contained within various compositions as discussed herein, for example, in liquid crystal multilamellar phosphatidylcholine. In addition, in certain embodiments as discussed below, the composition may be stable and can be stored for periods of time with little or no loss or reaction of the nitric oxide contained therein.

In one aspect, the present invention is useful for treating erectile dysfunction or sexual dysfunction. For example, the composition can be applied to the skin of a subject on or near a male or female genital region to treat sexual dysfunction and/or to enhance sexual performance or experience. In some embodiments, a composition is applied to the perineal region (e.g., penis), to the vulva, etc., to release nitric oxide to the skin and underlying tissue directly upon topical administration of the composition to the subject. For example, a composition of the invention may be applied to the genital perineal region or penis or portion thereof of a male subject to treat erectile dysfunction, to the vulva of a female subject to treat sexual dysfunction (or to any other portion at or near the genital perineal region in male or female subjects).

The composition, in yet another aspect, can be applied to the skin of a subject, for example, to a wound to promote wound healing. In some embodiments, compositions of the invention can be used to promote any wound healing by applying the composition to an existing wound. It should be appreciated that compositions of the invention may be used to treat or promote healing of any type of wound, including cuts, scrapes, other traumatic wounds, burns or other accidental wounds. Non-limiting examples of wounds include wound can be an anal fissure, a surgical site, a trauma site, a burn, an abrasion, a sunburn, a cut or laceration on the skin, or any other damaged region of the skin. In some embodiments, the composition is applied to a mucosal surface of the subject, for example, to the nose. Accordingly, compositions of the invention also may be used to treat wounds that result from surgical intervention (e.g., any medical intervention or operation that requires wound healing as part of the recovery process). It should be appreciated that compositions of the invention can be used prophylactically to a site (for example a surgical site) in anticipation of a wound. Accordingly, in some embodiments, a composition of the invention can be used to prepare a tissue site for wound healing prior to the wound (e.g., prior to surgery) and/or after the wound (e.g., and/or after surgery). In some embodiments, a composition of the invention may be applied to the surface of a wound or to skin prior to a wound.

In some embodiments, a composition of the invention may be applied to a surgical device, tool, or other substrate. For example, a composition of the invention may be applied to sutures, implants, surgical tools, or other substrates that may come into contact with wounded tissue (e.g., cut tissue) during surgery. In some embodiments, compositions of the invention may be provided as a cream or ointment as described in more detail herein. It also should be appreciated that compositions of the invention may be provided on surgical dressings, bandages, or other material that is to be contacted to a surgical wound. In some embodiments, a composition may be applied to a material or substrate immediately prior to use on a subject. However, in some embodiments, a material or substrate may be prepared (e.g., packaged, stored, or otherwise prepared) to contain a composition of the invention prior to use. For example, prepackaged bandages or surgical devices, sutures, or implants may be prepared and packaged with a coating of a composition of the invention. Compositions of the invention may be used for human or other animal subjects (male or female).

In still another aspect, a composition of the present invention may be applied to a subject to promote hair growth, for example in a region where hair growth is desired. In some embodiments, a composition can be applied to the skin of a subject, for example, to prevent or reduce hair loss, for example in a region where hair loss is undesirable. In some embodiments, a region targeted for hair growth and or a reduction in hair loss may be the skin surface of the scalp. In some embodiments, a subject may be a human. The subject may be male or female. In some embodiments, a subject may have lost hair (e.g., is bald, balding, or has thinning hair) and/or may be at risk of losing hair (e.g., due to age, a genetic risk and/or family history of hair loss). In some embodiments, the subject may have lost hair or be at risk for losing hair due to injury (e.g., trauma or burn) or due to a disease and/or treatment (e.g., chemotherapy).

According to some aspects of the invention, nitric oxide is useful as a therapeutic agent useful for in the promotion of healthy cells and tissues and/or because nitric oxide can act to increase local blood flow. It is generally believed that the therapeutic effect of nitric oxide owes largely to its cell signaling function, although there may also be other modes of action. Because nitric oxide is highly reactive (having a lifetime of a few seconds), yet diffuses freely across cell membranes, nitric oxide often acts as a transient paracrine (between adjacent cells) or autocrine (within a single cell) signaling molecule. Nitric oxide produced by one cell can penetrate through cell membranes to regulate the function of other cells, which may lead to cascading effects in biological systems. These are also known as the so-called nitric oxide pathways. For example, the endothelium (inner lining) of blood vessels can use nitric oxide to signal the surrounding smooth muscle to relax, thus resulting in vasodilation and increasing blood flow. Nitric oxide also may contribute to vessel homeostasis by inhibiting vascular smooth muscle contraction and growth, platelet aggregation, and leukocyte adhesion to the endothelium.

The human body produces nitric oxide naturally as needed. Nitric oxide may be biosynthesized endogenously from L-arginine, oxygen, and/or NADPH by various nitric oxide synthetase enzymes. Nitric oxide may also be generated by phagocytes (monocytes, macrophages, and neutrophils) as part of the human immune response. However, there often exists a need to provide additional quantities of nitric oxide for therapeutic reasons, or as dietary supplements. For example, nitric oxide may be introduced to subjects to stimulate or support vasodilatation, anti-inflammation, anti-bacteria, neurotransmission, modulation of the hair cycle, treatment of anal disorders and penile erections (through nitric oxide's ability to vasodilate), or the like. As dietary supplements, nitric oxide training gels, such as FORCE FACTOR® sold by General Nutrition Centers (GNC), are taken by athletes and others in the belief that nitric oxide will increase muscle strength and endurance, reduce warm-up related injuries, or decrease recuperation time.

Because nitric oxide is an unstable and reactive gas, therapeutic delivery of nitric oxide is usually accomplished by dosing a nitric oxide prodrug, also known as a nitric oxide donor, although in some cases, nitric oxide itself can be administrated by inhalation. The nitric oxide donor is typically formulated in a pharmaceutically accepted carrier for oral, topical, or other administration routes, and the nitric oxide donor subsequently releases nitric oxide after administration. Examples of such nitric oxide donors include L-arginine, nitroglycerin, and amyl nitrite. For subjects that suffer from symptoms that appear on skin (e.g. anal fissure) or the scalp (e.g. baldness), direct delivery of nitric oxide to the affected skin or scalp can be more effective and convenient, especially if long-term treatment is required. Topical application of nitric oxide can also reduce or eliminate the side effects associated with sustained increased levels of nitric oxide in the human body. For example, it has been discovered that high levels of nitric oxide may result in direct tissue damage and/or contribute to the vascular collapse associated with septic shock.

Until now, the art has been deficient in topical nitric oxide treatments. Some aspects of the present invention address this gap in the art and the therapeutic need by providing various compositions and methods that deliver nitric oxide topically. In some cases, these compositions and methods stimulate the absorption of nitric oxide into cells and tissues, and/or promote vasodilation of skin tissues. Certain aspects of the present invention thus permit treatment or prevention of various symptoms such as erectile dysfunction, hair loss, or wound healing.

Since nitric oxide is an unstable and reactive gas, entrapment, storage, and release of nitric oxide requires careful formulation in some embodiments of the invention. For example, nitric oxide readily reacts with water to form nitrous acid (HNO₂), and thus, certain embodiments of the invention include compositions or phases that are substantially free of water. As another example, in one set of embodiments, nitric oxide may be contained within a first phase comprising a lecithin such as phosphatidylcholine, which may be present within a second phase comprising an emulsifier, such as is discussed herein. Other components, for example, transdermal penetration enhancers, adjuvants, surfactants, lubricants, etc. can also be present in certain cases.

Thus, the compositions of the invention comprise, in certain aspects, a phase comprising phosphatidylcholine and/or other lecithins in which nitric oxide is contained within or “trapped.” The phosphatidylcholine or lecithin may be contained within a second phase, for example, comprising an emulsifier, which may cause the phosphatidylcholine or lecithin to form vesicles, e.g., micelles or liposomes. The phosphatidylcholine or lecithin composition can be unilamellar or multilamellar in some embodiments. In some instances, the presence of the second phase causes the phosphatidylcholine or lecithin to form a liquid crystal arrangement.

The nitric oxide is typically gaseous, and may be present within the composition as small bubbles and/or bound to lecithins or phosphatidylcholines within the composition. For example, the nitric oxide may be bound to double bonds present in the lecithins or phosphatidylcholines. Phosphatidylcholine is believed to stabilize and/or contain the nitric oxide. In some cases, stability of the composition can be achieved at room temperature (about 25° C.), and/or at other temperatures such as those described herein. Without wishing to be bound by any theory, it is believed that the phosphatidylcholine adopts a liquid crystal structure under such conditions, which can thereby contain the nitric oxide, e.g., as small gaseous bubbles, and/or through binding with lecithins or phosphatidylcholines.

Nitric oxide is typically reactive with water (e.g., forming nitrous acid), which contributes to its relatively short lifetime within the body or within other aqueous environments. Accordingly, in certain embodiments of the invention, the composition, or at least a phase of the composition comprising the nitric oxide (and/or the second phase, and/or one or more materials used to prepare a nitric oxide composition, and/or a nitric oxide composition prepared as described herein), is substantially free of water, e.g., comprising no more than about 10 wt %, no more than about 3 wt %, no more than about 1 wt %, no more than about 0.3 wt %, or no more than about 0.1 wt % water (i.e., relative to the weight of the overall composition). The composition may also have no more than about 1,000 ppm, no more than about 750 ppm, no more than about 500 ppm, no more than about 400 ppm, no more than about 300 ppm, no more than about 250 ppm, no more than about 200 ppm, no more than about 150 ppm, no more than about 100 ppm, no more than about 50 ppm, no more than about 25 ppm, or no more than about 10 ppm of water. In certain embodiments, no detectable water may be present in the composition, or at least within a phase of the composition comprising the nitric oxide. Any suitable technique can be used for determining the amount of water present in the composition, for example, Karl-Fisher titration. In some cases, the composition may also be free of any liquids that typically contain water, e.g., physiological buffers, body fluids, saline, or the like.

Any suitable amount of nitric oxide may be present within a composition prepared as described herein. For example, at least about 0.3 wt %, at least about 0.5 wt %, at least about 0.7 wt %, at least about 1 wt %, at least about 1.5 wt %, at least about 2 wt %, at least about 2.5 wt %, at least about 3 wt %, at least about 5 wt % at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, at least about 60 wt %, at least about 70 wt %, at least about 80 wt %, at least about 90 wt %, at least about 100 wt %, at least about 110 wt %, or at least about 120 wt % of the composition can be nitric oxide, where the basis of the weight percentage is the weight of the composition before nitric oxide is added. For example, the nitric oxide may be present at between 70 wt % and about 120 wt % of the composition. In some embodiments, the nitric oxide may be present at a concentration of at least about 400 mg/kg, at least about 450 mg/kg, at least about 500 mg/kg, at least about 550 mg/kg, at least about 570 mg/kg, at least about 600 mg/kg, at least about 650 mg/kg, at least about 700 mg/kg, at least about 750 mg/kg, at least about 800 mg/kg, at least about 850 mg/kg, at least about 950 mg/kg, or at least about 1000 mg/kg of the composition. In certain cases, the nitric oxide may be present at a concentration of no more than about 2000 mg/kg, no more than about 1500 mg/kg, no more than about 1000 mg/kg, no more than about 960 mg/kg, no more than about 900 mg/kg, no more than about 800 mg/kg, no more than about 700 mg/kg, or no more than about 600 mg/kg. For example, the nitric oxide may be present at a concentration of between about 570 mg/kg and about 960 mg/kg.

In some embodiments, nitric oxide is present within a first phase comprising a lecithin, such as phosphatidylcholine. Phosphatidylcholine (herein abbreviated “PC”) is a basic component of cell membrane bilayers and the main phospholipid circulating in the plasma of blood. Phosphatidylcholine typically has a phospholipid structure with a choline head group and a glycerophosphoric acid tail group. The tail group can be saturated or unsaturated. More than one tail group may be present in the phosphatidylcholine in some cases, and the tail groups may be the same or different. Specific non-limiting examples of phosphatidylcholines that could be used include one or a mixture of stearic, palmitic, margaric, and/or oleic acid diglycerides linked to a choline ester head group.

Phosphatidylcholines are a member of a class of compounds called lecithins. Typically, a lecithin is a composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and/or phospholipids. In some cases, other lecithins may be used, in addition to or instead of a phosphatidylcholine. Non-limiting examples of other lecithins include phosphatidylethanolamine, phosphatidylinositol, or phosphatidic acid. Many commercial lecithin products are available, such as, for example, Lecithol®, Vitellin®, Kelecin®, and Granulestin®. Lecithin is widely used in the food industry. In some embodiments, certain compositions of the invention can contain synthetic or natural lecithin, or mixtures thereof. Natural preparations are used in some cases because they exhibit desirable physical characteristics, and/or may be economical or nontoxic. However, in other embodiments, non-natural preparations are used, or the composition can include both natural and non-natural preparations.

Any suitable amount of phosphatidylcholine or lecithin may be present within the composition. For example, at least about 0.25 wt %, at least about 0.5 wt %, at least about 1 wt %, at least about 2 wt %, at least about 3 wt %, at least about 5 wt %, at least about 8 wt %, at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, at least about 60 wt %, at least about 70 wt %, at least about 80 wt %, or at least about 90 wt % of the entire composition can be a phosphatidylcholine or a lecithin. In some cases, the phosphatidylcholine or lecithin may be present at a concentration of no more than about 95 wt %, no more than about 90 wt %, no more than about 80 wt %, no more than about 70 wt %, no more than about 65 wt %, no more than about 60 wt %, no more than about 50 wt %, no more than about 40 wt %, no more than about 30 wt %, no more than about 20 wt %, or no more than about 10%. For instance, the phosphatidylcholine or lecithin may be present at between about 8 wt % and about 65 wt %, or between about 0 wt % and about 10 wt %, etc. One or more than one type of phosphatidylcholine or lecithin may be present.

Some delivery compositions of the present invention may contain polyenylphosphatidylcholine (herein abbreviated “PPC”). In some cases, PPC can be used to enhance epidermal penetration. The term “polyenylphosphatidylcholine,” as used herein, means any phosphatidylcholine bearing two fatty acid moieties, wherein at least one of the two fatty acids is an unsaturated fatty acid with at least two double bonds in its structure, such as linoleic acid.

Certain types of soybean lecithin and soybean fractions, for example, can contain higher levels of polyenylphosphatidylcholine, with dilinoleoylphosphatidylcholine (18:2-18:2 phosphatidylcholine) as the most abundant phosphatidylcholine species therein, than conventional food grade lecithin. Such lecithins may be useful in formulating certain delivery compositions. In some embodiments, conventional soybean lecithin may be enriched with polyenylphosphatidylcholine, for instance, by adding soybean extracts containing high levels of polyenylphosphatidylcholine. As used herein, this type of phosphatidylcholine is called “polyenylphosphatidylcholine-enriched” phosphatidylcholine (hereinafter referred to as PPC-enriched phosphatidylcholine), even where the term encompasses lecithin obtained from natural sources exhibiting polyenylphosphatidylcholine levels higher than ordinary soybean varieties. These products are commercially available, for example, from American Lecithin Company, Rhone-Poulenc and other lecithin vendors. American Lecithin Company markets its products with a “U” designation, indicating high levels of unsaturation; Rhone-Poulenc's product is a soybean extract containing about 42% dilinoleoylphosphatidylcholine and about 24% palmitoyllinoleylphosphatidylcholine (16:0 to 18:2 of PC) as the major phosphatidylcholine components. Another example of a suitable polyenylphosphatidylcholine is NAT 8729 (also commercially available from vendors such as Rhone-Poulenc and American Lecithin Company).

Any suitable amount of polyenylphosphatidylcholine may be present within the composition. For example, at least about 0.25 wt %, at least about 0.5 wt %, at least about 1 wt %, at least about 2 wt %, at least about 3 wt %, at least about 5 wt %, at least about 8 wt %, at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, at least about 60 wt %, at least about 70 wt %, at least about 80 wt %, or at least about 90 wt % of the composition can be polyenylphosphatidylcholine. In some cases, the polyenylphosphatidylcholine may be present at a concentration of no more than about 95 wt %, no more than about 90 wt %, no more than about 80 wt %, no more than about 70 wt %, no more than about 65 wt %, no more than about 60 wt %, no more than about 50 wt %, no more than about 40 wt %, no more than about 30 wt %, no more than about 20 wt %, or no more than about 10%. For instance, the polyenylphosphatidylcholine may be present at between about 8 wt % and about 65 wt %. In some embodiments, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, at least about 60 wt %, at least about 70 wt %, at least about 80 wt %, at least about 90 wt %, or about 100 wt % of all of the phosphatidylcholine or lecithin in the composition is polyenylphosphatidylcholine.

While not wishing to be bound to any theory, it is believed that the PPC-enriched phosphatidylcholine forms a bilayer enveloping nitric oxide (and in some embodiments, other adjunct ingredients, if present) to create the drug delivery composition. The PPC-enriched phosphatidylcholine is believed to contribute to the stability of the nitric oxide, for example, by shielding the nitric oxide from water, and/or by enhancing its penetration into the skin or other area, e.g., a mucosal surface.

The first phase also comprises, in some embodiments of the invention, a fatty acid ester. Non-limiting examples include ascorbate palmitate or isopropyl palmitate. In some cases, the fatty acid ester is used as a preservative or an antioxidant. The composition can include any suitable amount of fatty acid ester, for example, at least about 1 wt %, at least about 3 wt %, at least about 5 wt %, at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, etc. In some cases, no more than about 60 wt %, no more than about 50 wt %, no more than about 40 wt %, no more than about 30 wt %, no more than about 20 wt %, no more than about 18 wt %, no more than about 15 wt %, no more than about 12 wt %, or no more than about 10 wt % of the composition is fatty acid ester. For example, the composition may be between about 0 wt % and about 10 wt % fatty acid ester. The composition may include one or more than one fatty acid ester.

In certain embodiments, a drug delivery composition such as those described herein can be formulated to include a second phase. Typically, the second phase is substantially immiscible with the first phase comprising phosphatidylcholine or lecithin. Two phases that are substantially immiscible are able to form discrete phases when exposed to each other at ambient conditions (e.g., 25° C. and 1 atm) for extended periods of time (e.g., at least about a day). The phases can be separate identifiable phases (e.g., one may float above the other), or in some cases, the phases are intermingled, e.g., as in an emulsion. The stability of the discrete phases may be kinetic and/or thermodynamic in nature, in various embodiments.

In one set of embodiments, the second phase may comprise an emulsifier which causes the first phase comprising phosphatidylcholine or lecithin to form a liquid crystal, and/or vesicles such as micelles or liposomes. Typically, in a liquid crystal phase, vesicular structures such as micelles, liposomes, hexagonal phases, or lipid bilayers can be formed. In some cases, multilamellar structures may be present within the liquid crystal phase, although in other cases, only unilamellar structures may be present. For example, in certain cases, the PPC-enriched phosphatidylcholine can be loosely arranged in a multilamellar fashion, with nitric oxide and optional adjunct ingredients being bonded or otherwise entrapped or contained within the lipid bilayers formed therein. In some cases, the first phase (e.g., comprising PPC-enriched phosphatidylcholine) and the second phase can form a structure such as is disclosed in U.S. Pat. No. 7,182,956 to Perricone, et al. This is believed (without wishing to be bound by any theory) to form a loosely arranged, yet stable, PPC-enriched phosphatidylcholine-drug complex that may allow penetration and delivery of nitric oxide and optional adjunct ingredients to the skin, e.g., to the dermal vasculature, or to a mucosal surface.

In one set of embodiments, the second phase comprises an emulsifier. The emulsifier, in one embodiment, is a substance that is able to stabilize an emulsion by increasing its kinetic stability. The emulsifier may also be chosen in some cases to be relatively inert or non-toxic relative to the skin or to a mucosal surface.

In some embodiments, the second phase may comprise a polyglycol. The polyglycol may include a polyhydric alcohol of a monomeric glycol such as polyethylene glycol (PEG) and/or polypropylene glycol (PPG). For example, the PEG or PPG may be PEG or PPG 200, 300, 400, 600, 1,000, 1,450, 3,350, 4,000, 6,000, 8,000, and 20,000, where the number indicates the approximate average molecular weight of the PEG or PPG. As is understood by those of ordinary skill in the art, a polyglycol composition often will comprise a range of molecular weights, although the approximate average molecular weight is used to identify the type polyglycol. More than one PEG and/or PPG can also be present in certain instances.

The second phase may comprise a surfactant in some embodiments. Non-limiting examples of surfactants include a siloxylated polyether comprising dimethyl, methyl(propylpolyethylene oxide propylene oxide, acetate) siloxane commercially available from vendors such as Dow Corning (Dow Corning 190 surfactant). Other examples of materials that can be used as (or within) the second phase include, but are not limited to, 1,2-propanediol, or silicone fluids containing low viscosity polydimethylsiloxane polymers, methylparaben (p-hydroxy benzoic acid methyl ester) commercially available from vendors such as Dow Corning (Dow Corning 200 silicone fluid). Still other examples include various siloxane or silicone compounds, e.g., hexamethyldisiloxane, amodimethicone, phenyltrimethicone, etc.

Additionally, purified water may be added to the second phase in some embodiments, although in other cases, little or no water is present in the second phase. For example, the first phase, the second phase, can contain less than 10%, less than 5%, less than 2%, less than 1%, or less that 0.05% (e.g., wt %) of water relative to the weight of the respective phase or of the entire composition. In some cases, the second phase may also comprise adjunct ingredients such as those described herein.

The second phase may include any one, or more than one, of the materials described above. In addition, any suitable amount of second phase can be used in accordance with various embodiments of the invention. For example, the second phase may be present at at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, at least about 50 wt %, at least about 60 wt %, at least about 70 wt %, at least about 80 wt %, or at least about 90 wt % of the composition. In some cases, the ratio of the first phase (e.g., comprising phosphatidylcholine or lecithin) to the second phase can be at least about 1:3, at least about 1:2, at least about 1:1, at least about 2:1, at least about 3:1, or at least about 4:1, etc.

In another set of embodiments, the composition may also include one or more transdermal penetration enhancers. Examples of transdermal penetration enhancers include, but are not limited to, 1,3-dimethyl-2-imidazolidinone or 1,2-propanediol. Other examples include cationic, anionic, or nonionic surfactants (e.g., sodium dodecyl sulfate, polyoxamers, etc.); fatty acids and alcohols (e.g., ethanol, oleic acid, lauric acid, liposomes, etc.); anticholinergic agents (e.g., benzilonium bromide, oxyphenonium bromide); alkanones (e.g., n-heptane); amides (e.g., urea, N,N-dimethyl-m-toluamide); organic acids (e.g., citric acid); sulfoxides (e.g., dimethylsulfoxide); terpenes (e.g., cyclohexene); ureas; sugars; carbohydrates or other agents. The transdermal penetration enhancers can be present in any suitable amount within the composition. For example, at least about 10 wt %, at least about 20 wt %, at least about 30 wt %, at least about 40 wt %, or at least about 50 wt % of the composition may comprise one or more transdermal penetration enhancers. In some cases, no more than about 60 wt %, no more than about 50 wt %, no more than about 40 wt %, no more than about 30 wt %, no more than about 20 wt %, no more than about 10 wt %, no more than about 9 wt %, or no more than about 5 wt % of the composition comprises transdermal penetration enhancers. For example, the composition may have between about 0 wt % and about 5 wt % of one or more transdermal penetration enhancers.

As a specific non-limiting example of one set of embodiments, a polyenylphosphatidylcholine comprises a certain material with the trade name NAT 8729, and optionally at least one polyglycol (polyhydric alcohol of a monomeric glycol such as polyethylene glycol 200, 300, 400, 600, 1,000, 1,450, 3,350, 4,000, 6,000, 8,000 and 20,000). The composition can also comprise a PPC-enriched phosphatidylcholine material that is present within the first or second phase, e.g., comprising nitric oxide. The second phase may also comprise a surfactant such as a siloxylated polyether comprising dimethyl, methyl(propylpolyethylene oxide propylene oxide, acetate) siloxane commercially available from vendors such as Dow Corning (Dow Corning 190 surfactant) and lubricant such as silicone fluids containing low viscosity polydimethylsiloxane polymers, methylparaben (p-hydroxy benzoic acid methyl ester) commercially available from vendors such as Down Corning (Dow Corning 200 silicone fluid).

In some embodiments, various compositions of the invention are formulated to be substantially clear or substantially transparent. Transparency may be useful, for instance, for product acceptance in the marketplace, e.g., when applied to the skin of a subject. However, in other embodiments, the composition is not necessarily transparent. Certain substances can be useful in providing a substantially transparent composition, for example, fatty acid esters such as ascorbate palmitate or isopropyl palmitate. In one set of embodiments, the composition may be substantially transparent such that incident visible light (e.g., have wavelengths of between about 400 nm and about 700 nm) can be transmitted through 1 cm of the composition with a loss in intensity of no more than about 50%, about 60%, about 70%, about 80%, or about 90% relative to the incident light. In some embodiments, there may be no substantial difference in the wavelengths that are absorbed by the composition (i.e., white light passing through the composition appears white), although in other cases, there can be more absorption at various wavelengths (for example, such that white light passing through the composition may appear colored).

Other components may also be present within the composition, in accordance with certain embodiments of the invention. For example, the composition may include volatile organic fluids, fatty acids, volatile aromatic cyclic compounds, high molecular weight hydrocarbons, or the like.

In accordance with certain aspects of the invention, the composition may be prepared by mixing a first phase and a second phase together, then passing nitric oxide through the mixture. As discussed above, the second phase can comprise an emulsifier, or any other components discussed herein. The first phase may comprise a lecithin such as phosphatidylcholine and/or polyenylphosphatidylcholine, e.g., PPC-enriched phosphatidylcholine, for instance, as described herein. In some embodiments, other components are also mixed into the composition, before or after (or while) adding nitric oxide, for example, transdermal penetration enhancers, adjuvants, polyglycols (e.g., PEG and/or PPG), surfactants, lubricants, etc. as discussed herein. In some embodiments, however, nitric oxide may be passed through the first phase prior to mixing of the first phase with the second phase.

In one set of embodiments, after forming the mixture, nitric oxide can be passed into or through the mixture, for example, by blowing bubbles of nitric oxide through the mixture. Nitric oxide may be delivered into the mixture under pressures such as between about 3,000 Pa and about 15,000 Pa, between about 5,000 Pa and about 10,000 Pa, or between about 6,000 Pa and about 8,000 Pa, and/or temperatures such as between about 0° C. and about 50° C., between about 20° C. and about 35° C., or about 25° C. and about 30° C. However, higher or lower pressures also may be used in some embodiments as aspects of the invention are not limited in this respect.

In certain embodiments, the nitric oxide is bubbled through the mixture until the mixture begins to at least partially solidify. As an example, the viscosity of the mixture may increase to at least about 1,000 cP, at least about 2,000 cP, at least about 3,000 cP, at least about 5,000 cP, at least about 7,000 cP, at least about 10,000 cP, at least about 12,000 cP, at least about 15,000 cP, at least about 20,000 cP, at least about 30,000 cP, at least about 40,000 cP, at least about 50,000 cP, at least about 60,000 cP, at least about 70,000 cP, or at least about 80,000 cP. The nitric oxide can be passed through the mixture as pure nitric oxide, and/or with other gases (e.g., a noble gas, for example, argon). In some cases, a nitric oxide donor may be passed into the mixture, and therein, at least some of the nitric oxide donor can be converted into nitric oxide. In other embodiments, however, the final composition may have lower viscosities, for example, such that the composition is liquid, or could be sprayed onto the skin or onto a mucosal surface.

In one set of embodiments, the nitric oxide can be bubbled through the mixture to cause the viscosity of the mixture to increase. For example, the viscosity can increase until the mixture begins to form a gel, a cream, a lotion, an ointment, a solid “stick,” or the like. A cream may be, for example, a semi-solid emulsion, e.g., comprising a first phase and a second phase. The first phase may be discontinuous (e.g., comprising small droplets or vesicles, such as is discussed herein) and the second phase may be continuous, or vice versa. In some cases, however, both the first phase and the second phase are co-continuous within the mixture.

In some embodiments of the invention, a composition may be prepared as discussed above, then diluted, e.g., with a diluent, to produce a final composition. For example, a “stock” composition may be initially prepared, e.g., having a relatively high nitric oxide concentration, then the stock composition diluted to produce a final composition, e.g., before use, before storage, before packaging, etc. In some embodiments, the diluent used may be a component as discussed herein (for example, forming at least a portion of the second phase), and the same or different materials than may be present in the initial composition may be used. The dilution ratio (amount of diluent added, relative to the initial composition) may be at least about 2, at least about 3, at least about 5, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 50, or at least about 100, or any other suitable factor.

A composition may be prepared and/or stored at any suitable temperature and under any suitable conditions. In some embodiments, for instance, a composition can be prepared and/or stored under limited or no oxygen conditions, as oxygen can adversely react with nitric oxide. The composition can also be prepared and/or stored under limited or no nitrogen and/or carbon dioxide, as both can also react adversely with nitric oxide. For instance, the composition may be prepared and/or stored in a sealed environment (e.g., stored in a sealed container). The sealed environment (e.g., container) can be at least substantially devoid of gas, and/or contains a gaseous mixture that excludes, or at least is depleted in, oxygen. In some embodiments, an environment depleted in oxygen may have less than about 20%, less than about 15%, less than about 10%, less than about 5%, about 1% or less, about 0.1% or less, about 0.01% or less, about 0.001% or less, oxygen (e.g., as a wt % or as molar % per volume). For example, the gaseous mixture may include a noble gas, such as argon, helium, neon, etc. In one set of embodiments, the container may comprise a multi-layered metallic and/or polymeric barrier, e.g., formed from Glaminate® (American Can Company). For instance, the container may have the shape of a tube. Thus, in certain embodiments, the container is substantially resistant to oxygen permeation, nitrogen permeation, and/or carbon dioxide permeation. In certain embodiments, the container is substantially watertight, for example, such that substantially no water is absorbed by the container, or such that no water is able to pass through the container even if the container is filled with water.

As previously discussed, nitric oxide can react with water, and thus, compositions described herein may be prepared and/or stored under conditions where substantially no water is present. For example, nitric oxide and/or a nitric oxide containing preparation described herein may be prepared and/or stored under relatively low relative humidities (e.g., less than about 50% RH, less than about 40% RH, less than about 30% RH, less than about 20% RH, or less than about 10% RH), and/or in the presence of a suitable desiccant, such as phosphorous pentoxide or silica gel.

In certain embodiments, the mixture may be mixed with or otherwise include adjunct ingredients, if applicable, and nitric oxide may be introduced to the mixture, e.g., bubbles of nitric oxide gas may be blown into the mixture until the mixture hardens to obtain the desired final composition. As a specific non-limiting example, a nitric oxide composition may be formed by preparing a non-liposome multilamellar liquid crystal phosphatidylcholine phase, for example, by providing a polyglycol, then introducing phosphatidyl choline into the glycol at room temperature to form a phosphatidylcholine solution. The phosphatidylcholine often comes as a solid (e.g., as a “brick” of material), and the phosphatidylcholine may be broken down into smaller pieces to aid in mixing, e.g., by “shaving” or grinding the phosphatidylcholine solid. The phosphatidylcholine solution is mixed until the phosphatidylcholine solution is substantially clear, then one may warm the phosphatidylcholine solution to 40° C., mill the warmed solution (i.e., low agitation after the initial mixing), combine siloxylated polyether and polydimethylsiloxane to form a fluid, add the fluid to the warmed solution and milling until the solution is clear, adding methyl paraben or other suitable lubricant to the solution and milling until the methyl paraben dissolves in the solution, warm water to 40° C. and adding the warmed water slowly to the solution, and then ceasing milling of the solution and “sweeping” the solution (e.g., with a sweep mixer) to cool to room temperature. Nitric oxide gas can then be bubbled or otherwise introduced into the solution while cooling the solution until the solution begins to harden or becomes stiff, e.g., having the consistency of a gel or a cream, such as previously described. In some cases, the resulting composition is sealed in a container, for example, as discussed herein. Any suitable container may be used, e.g., a tube or a bottle. In addition, the composition (e.g., within the container) may be stored at room temperature, or any other suitable temperature. For example, a composition of the invention may be stored at or below 80° C., e.g., at or below room temperature (about 25° C.) or in a refrigerator (e.g., at 4° C.) for extended period of storage, for instance, to prevent nitric oxide leakage or denaturing.

It is surprising that, according to some embodiments, nitric oxide not only can be entrapped in phosphatidylcholine or lecithin compositions such as those described herein, but also that such entrapped compositions may have a long shelf life, especially when refrigerated. No loss or reaction of nitric oxide is expected during extended refrigerated storage, at least under certain conditions. For instance, in certain embodiments, the composition may be stored at temperatures of less than about 80° C., less than about 70° C., less than about 60° C., less than about 50° C., less than about 40° C., less than about 30° C., less than about 25° C., less than about 20° C., less than about 15° C., less than about 10° C., less than about 5° C., less than about 0° C., etc., for extended periods of time, e.g., at least about a day, at least about a week, at least about 4 weeks, at least about 6 months, etc.

Without wishing to be bound by theory, it is believed that nitric oxide forms reversible physical bonds, similar to hydrogen bonds or van der Waals forces, with phosphatidylcholine or other lecithin molecules, e.g., containing one or more double bonds, which may allow nitric oxide to become entrapped and thereby remain intact for an extended period of time, e.g., during storage. These physical bonds, however, are believed to be not very stable, and may in some cases be easily broken up, for example, upon various physical agitations such as rubbing the composition against skin or a mucosal surface, thereby releasing the entrapped nitric oxide. While others have stabilized other substances or drugs within phosphatidylcholine or lecithin compositions or vesicles, for example, protein drugs such as insulin, it is surprising that a small, highly reactive molecule such as NO could similarly be stabilized, especially when it would have been expected that a molecule as small as NO would readily diffuse away from such compositions and/or would have reacted with water that is typically present within such compositions.

In some embodiments, it is believed that other species reactive with water could also be similarly stabilized, e.g., within a composition as herein described. Any species that ordinarily reacts with water could be stabilized within such compositions. Examples of such species include, but are not limited to, lithium, or drugs or polymers with labile bonds susceptible to hydrolysis, for instance, certain peptides, polysaccharides, polylactic acid, polyglycolic acid, etc.

In certain aspects of the invention, a composition such as those described herein can be administered to a subject, such as a human subject, by rubbing it on the skin or a mucosal surface of the subject, e.g., in areas located at or at least within the vicinity of a desired target area. Without wishing to be bound by any theory, it is believed that phosphatidylcholine provides or facilitates delivery of nitric oxide to the skin or a mucosal surface, and/or to tissues below the skin or mucosal surface, allowing nitric oxide to be delivered to a target area. In some embodiments, the composition can be applied, by rubbing the composition topically against the skin, or to the mucosal surface, which allows the composition (or at least, nitric oxide) to be absorbed by the skin or mucosal surface. The composition can be applied once, or more than once. For example, the composition may be administered at predetermined intervals. In some embodiments, for instance, the composition may be applied once per day, twice per day, 3 times per day, 4 times per day, once every other day, once every three days, once every four days, etc. The amount of nitric oxide necessary to bring about the therapeutic treatment is not fixed per se, and may depend upon factors such as the desired outcome, the type and severity the disease or condition, the form of nitric oxide, the concentration of nitric oxide present within the composition, etc.

Thus, another aspect of the invention provides methods of administering any composition such as is discussed herein to a subject. When administered, the compositions of the invention are applied in a therapeutically effective, pharmaceutically acceptable amount as a pharmaceutically acceptable formulation. Any of the compositions of the present invention may be administered to the subject in a therapeutically effective dose. When administered to a subject, effective amounts will depend on the particular condition being treated and the desired outcome. A therapeutically effective dose may be determined by those of ordinary skill in the art, for instance, employing factors such as those described herein and using no more than routine experimentation.

In certain embodiments of the invention, the administration of the composition of the invention may be designed so as to result in sequential exposures to the composition over a certain time period, for example, hours, days, weeks, months, or years. This may be accomplished, for example, by repeated administrations of a composition of the invention by one or more of the methods described herein, or by a sustained or controlled release delivery system in which the composition is delivered over a prolonged period without repeated administrations. Administration of the composition using such a delivery system may be, for example, by a transdermal patch. Maintaining a substantially constant concentration of the composition may be preferred in some cases.

For certain chronic treatments or therapies, it is contemplated that a composition as discussed herein may be used to deliver nitric oxide to the skin or mucosal surface at a relatively high concentration during an initial treatment, and the amount of nitric oxide may be lowered or “titrated” down to a relatively lower concentration maintenance dose or amount. A nitric oxide containing composition as described herein can be used to promote vasodilation of blood vessels within and/or under the skin. As a specific example, a composition described herein may be used for certain treatments of hair loss or wounds, e.g., anal fissures. In some cases, gradual improvement may be observed with successive applications.

In one set of embodiments, a composition such as is discussed herein may be applied to the skin or mucosal surface of a subject, e.g., at any suitable location. The composition may be contacted using any suitable method. For example, the composition may be rubbed on, poured on, applied with an applicator (e.g., a gauze pad, a swab, a bandage, etc.), or the like. In some cases, the composition can be a liquid, a gel, a cream, a lotion, an ointment, a solid “stick,” or the like, that can be applied to the skin or mucosal surface by hand, for example, by rubbing or spraying.

In certain embodiments, the composition is applied to a mucosal surface of the subject. For example, the composition may be applied to the nose or nostrils, the mouth, the lips, the eyelids, the ears, the genital area (of either male or female subjects), or the anus.

The composition may be applied, in certain embodiments, at or near a genital region of the skin of a male or a female subject, e.g., to treat sexual dysfunction. For example, the composition may be applied to the penis of a male subject or to the vulva of a female subject, or to any other suitable genital perianal region. In certain embodiments, for instance, the composition is used to treat erectile dysfunction. In some cases, the composition can be applied to a condom or other suitable sexual aid. The composition can be applied, for example, just before the subject engages in sexual activity.

Compared to other means of administration, the use of topical (or mucosal) administration in certain embodiments of the present invention has various advantages, including one or more of the following. In some cases, administration of a composition and delivery of nitric oxide as discussed herein is easier and more effective than other drug administration routes, for example, oral delivery. Unlike oral administration where a substantial amount of nitric oxide may be destroyed during the digestive process, nitric oxide delivered topically or to a mucosal surface is not exposed to the digestive tract. Topical or mucosal application may also allow, in some instances, relatively steady delivery of nitric oxide to the desired target area without the cyclic dosages typical of orally or parenterally administered drugs. In some embodiments, topical or mucosal application may also avoid toxic side effects associated with sustained increased levels of nitric oxide typical of oral or parenteral administration.

Compared to other topical or mucosal delivery systems that employ nitric oxide donors (an entity that is able to release nitric oxide, such as L-arginine, nitroglycerin, or amyl nitrite) as a nitric oxide source, various aspects of the present invention utilizing nitric oxide gas have several advantages, including one or more of the following. Nitric oxide can be released relatively quickly in some embodiments, because the release does not necessarily involve chemical transformations of nitric oxide donors to release nitric oxide. The concentration of nitric oxide can accumulate quickly upon topical (or mucosal) administration, leading to good therapeutic effect in certain embodiments of the invention. Thus, for example, rapid nitric oxide delivery may provide quicker effect in addressing issues of erectile dysfunction (or other sexual dysfunction in either male or female subjects) than is possible with oral dosage forms such as sildenafil. In other applications, it is expected that nitric oxide can be similarly delivered rapidly. In some embodiments, the release rate of nitric oxide can be controlled, for instance, by physical actions (e.g., by controlling how much of the composition is applied to the skin), in comparison to nitric oxide donors which release nitric oxide upon chemical stimulation. Moreover, certain embodiments of the present invention employ phosphatidylcholine, a component of cell membranes, as a carrier which improves the penetration and absorption of nitric oxide into cells and tissues. Thus, certain compositions of the present invention will be non-toxic or biocompatible.

The compositions of the present invention may additionally comprise one or more adjunct ingredients, for instance, pharmaceutical drugs or skin care agents. For example, compositions of the invention may include adjuvants such as salts, buffering agents, diluents, excipients, chelating agents, fillers, drying agents, antioxidants, antimicrobials, preservatives, binding agents, bulking agents, silicas, solubilizers, or stabilizers. Non-limiting examples include species such as calcium carbonate, sodium carbonate, lactose, kaolin, calcium phosphate, or sodium phosphate; granulating and disintegrating agents such as corn starch or algenic acid; binding agents such as starch, gelatin or acacia; lubricating agents such as magnesium stearate, stearic acid, or talc; time-delay materials such as glycerol monostearate or glycerol distearate; suspending agents such as sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone; dispersing or wetting agents such as lecithin or other naturally-occurring phosphatides; thickening agents such as cetyl alcohol or beeswax; buffering agents such as acetic acid and salts thereof, citric acid and salts thereof, boric acid and salts thereof, or phosphoric acid and salts thereof; or preservatives such as benzalkonium chloride, chlorobutanol, parabens, or thimerosal. Suitable concentrations can be determined by those of ordinary skill in the art, using no more than routine experimentation. Those of ordinary skill in the art will know of other suitable formulation ingredients, or will be able to ascertain such, using only routine experimentation.

Preparations can include sterile aqueous or nonaqueous solutions, suspensions and emulsions, which can be isotonic with the blood of the subject in certain embodiments. Examples of nonaqueous solvents are polypropylene glycol, polyethylene glycol, vegetable oil such as olive oil, sesame oil, coconut oil, arachis oil, peanut oil, mineral oil, organic esters such as ethyl oleate, or fixed oils including synthetic mono or di-glycerides. Aqueous solvents include water, alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media. Parenteral vehicles include sodium chloride solution, 1,3-butandiol, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's or fixed oils. Intravenous vehicles include fluid and nutrient replenishers, electrolyte replenishers (such as those based on Ringer's dextrose), and the like. Preservatives and other additives may also be present such as, for example, antimicrobials, antioxidants, chelating agents and inert gases and the like. Those of skill in the art can readily determine the various parameters for preparing and formulating the compositions of the invention without resort to undue experimentation.

In another aspect, the present invention is directed to a kit including one or more of the compositions discussed herein. A “kit,” as used herein, typically defines a package or an assembly including one or more of the compositions of the invention, and/or other compositions associated with the invention, for example, as described herein. Each of the compositions of the kit may be provided in liquid form (e.g., in solution), or in solid form (e.g., a dried powder). In certain cases, some of the compositions may be constitutable or otherwise processable (e.g., to an active form), for example, by the addition of a suitable solvent or other species, which may or may not be provided with the kit. Examples of other compositions or components associated with the invention include, but are not limited to, solvents, surfactants, diluents, salts, buffers, chelating agents, fillers, antioxidants, binding agents, bulking agents, preservatives, drying agents, antimicrobials, needles, syringes, packaging materials, tubes, bottles, flasks, beakers, dishes, frits, filters, rings, clamps, wraps, patches, containers, and the like, for example, for using, administering, modifying, assembling, storing, packaging, preparing, mixing, diluting, and/or preserving the compositions components for a particular use, for example, to a sample and/or a subject.

A kit of the invention may, in some cases, include instructions in any form that are provided in connection with the compositions of the invention in such a manner that one of ordinary skill in the art would recognize that the instructions are to be associated with the compositions of the invention. For instance, the instructions may include instructions for the use, modification, mixing, diluting, preserving, administering, assembly, storage, packaging, and/or preparation of the composition and/or other compositions associated with the kit. In some cases, the instructions may also include instructions for the delivery and/or administration of the compositions, for example, for a particular use, e.g., to a sample and/or a subject. The instructions may be provided in any form recognizable by one of ordinary skill in the art as a suitable vehicle for containing such instructions, for example, written or published, verbal, audible (e.g., telephonic), digital, optical, visual (e.g., videotape, DVD, etc.) or electronic communications (including Internet or web-based communications), provided in any manner.

U.S. Provisional Patent Application Ser. No. 61/453,836, filed Mar. 17, 2011, entitled “Topical Nitric Oxide Systems,” by Nicholas V. Perricone is incorporated herein by reference in its entirety.

The following examples are intended to illustrate certain embodiments of the present invention, but do not exemplify the full scope of the invention.

Example 1

This example illustrates one technique for preparing a composition in accordance with one embodiment of the invention. An accurate amount of a carrier (HNC 167-62) (see below) was introduced into a system. The carrier weight used in these experiments was approximately 250 g and the vessel size was 500 ml. The vessel was equipped with a mechanical stirrer, gas inlet, and gas outlet and was previously purged with argon for about an hour. The temperature of the carrier was kept at about 25-30° C. NO gas regulated at 5 psi (1 psi is about 6,900 Pa) and was then introduced at a controlled rate of about 1 bubble/s with continuous stirring. The color, consistency, and viscosity of the carrier did not appear to change if NO was bubbled for 30 minutes to 2 hours. After 6 hours, the weight of the carrier had increased by 0.15%, by 12 hours by 0.25%, and by 24 hours by 0.56%. These increases in weight were believed to be significant considering the relative small molecular weight of NO versus the carrier. Although there was a slight change in color during the experiment (the color changed to slightly more orange), IR spectrum analysis of the final product did not show any change versus the initial carrier, indicating no noticeable chemical change in the carrier. The carrier also can solidify upon cooling if the carrier is initially a solid at lower temperature. Accordingly, this example demonstrates that a composition containing NO can be prepared in accordance with one embodiment of the invention.

Example 2

In this example, six experiments were carried out to investigate the interaction of nitric oxide with three carriers (HNC 157-62, HNC 157-65, and HNC 157-69) as well as with 1,3-propanediol, using experimental conditions similar to that described for Example 1. In addition three experiments were performed to prepare carriers containing 800 ppm and 500 ppm nitric oxide. HNC 157-62 was formed of 65% Phospholipon-90G (American Lecithin Company), 18% isopropyl palmitate (Kraft Chemicals), 8% capric caprylic triglycerides (RITA Corp.), and 9% propanediol (Dupont). HNC 157-65 was formed of 65% Phospholipon-90G, 13% isopropyl palmitate, 14% capric caprylic triglycerides, 3% propanediol, and 5% dimethyl isosorbide (Croda). HNC 157-69 was formed from 65% Phospholipon-90G, 16% isopropyl palmitate, and 19% capric caprylic triglycerides.

The compositions were generally prepared as follows. Isopropyl palmitate, capric caprylic triglyceride, propanediol (for HNC 157-62 and HNC 157-65), and dimethyl isosorbide (for HNC 157-65) were mixed together and warmed to 40° C. Phospholipon-90G was then gradually added to this liquid mixture by mixing it. Phospholipon-90G is typically received as individual pellets, and is mixed into the solution until fully dissolved. The mixture was subsequently filtered through a sieve to remove any undissolved Phospholipon-90G.

Accordingly, the HNC carriers included 1,3-propanediol, Phospholipon-90G, isopropyl palmitate, capric and/or caporic triglycerides, and Arlasolve DMI (ICI America or Croda). Isopropyl palmitate, the capric and/or caporic triglycerides, and Arlasolve DMI are expected to be chemically inert towards nitric oxide, while the literature suggests that 1,2-propanediol and glycerol may be able to react with nitric oxide gas to form mononitrates. Accordingly, it would be expected that 1,3-propanediol may also react with NO to form mononitrates:

In addition, Phospholipon-90G is derived from soybean and contains esters of unsaturated fatty acids such as oleic, linoleic, and linolenic acids, and thus, the unsaturated fatty acid part of Phospholipon-90G would react with nitric oxide to lead to a variety of nitrated products.

Each carrier was taken in a 500 mL three necked flask equipped with a mechanical stirrer, gas inlet and a gas outlet. The system was purged with argon for one hour at room temperature (25° C.). Then nitric oxide gas was bubbled into the system. Then, nitric oxide gas was bubbled through carrier for stipulated amount of time. The changes in weight and color were noted. The details of individual experiments were as follows.

Experiment 1. The carrier was HNC 157-62. Nitric oxide gas was bubbled for 24 hours at 25° C. The initial weight of carrier was 168.53 g., and the final weight was 169.48 g. The net weight gained was 0.95 g and the percentage weight gain was 0.56%.

Experiment 2. The carrier used was HNC 157-62. Nitric oxide gas was bubbled for 48 hours at 25° C. The initial weight of carrier was 171.31 g., and the final weight was 174.21 g. The net weight gained was 2.90 G and the percentage weight gain was 1.69%.

Experiment 3. In order to differentiate between chemical reaction vs. physical absorption, the above reaction mixtures were heated at 55-60° C. for four hours. Minimal loss of weight was observed (˜200 mg), indicating no loss of absorbed nitric oxide gas. However, more intense orange color developed during this process, indicating some decomposition of the nitrites formed.

Experiment 4. The carrier used was HNC 157-65. Nitric oxide gas was bubbled for 24 hours at 25° C. The initial weight of carrier was 171.66 g., and the final weight was 172.98 g. The net weight gained was 1.32 g and percentage weight gain was 0.77%.

Experiment 5. The carrier used was HNC 157-69 (same as HNC 157-62, except it had no 1,3-propanediol). Nitric oxide gas was bubbled for 40 hours at 25° C. The initial weight of carrier was 171.02 g., and the final weight was 171.97 g. The net weight gained was 0.95 g and the percentage weight gain was 0.56%.

Experiment 6. Nitric oxide gas was bubbled through 1,3-propanediol (neat) for 40 hours at 25° C. The initial weight of the 1,3-propanediol was 178.81 g., and the final weight was 178.97 g. The net weight gained was 0.16 g and the percentage weight gain was 0.09%.

Experiment 7. For preparation of 800 ppm NO, the carrier used was HNC 157-62. Nitric oxide gas was bubbled for 2 hours at 25° C. The initial weight of carrier was 238.16 g., and the final weight was 238.35 g. The net weight gained was 0.19 g and the percentage weight gain 0.0798% (˜800 ppm). See entry 5 in Table 1.

Experiment 8. For preparation of 500 ppm NO, the carrier used was HNC 157-65. Nitric oxide gas was bubbled for 2 hours at 25° C. The initial weight of carrier was 250.37 g., and the final weight was 250.50 g. The net weight gained was 0.13 g and the percentage weight gain was 0.0519% (˜500 ppm). See entry 6 in Table 1.

Experiment 9. For preparation of 800 ppm NO, the carrier used was HNC 157-62. Nitric oxide gas was bubbled for 15 min at 25° C. The initial weight of carrier was 252.24 g., and the final weight was 252.45 g. The net weight gained was 0.21 g and the percentage weight gain 0.083% (˜800 ppm).

These experiments were conducted with carriers the HNC 157-62, HNC 157-65, HNC 157-69, and 1,3-propanediol.

As described above and in Table 1, weight gains ranging from 0.5% to 1.7% were observed when nitric oxide gas was passed through the carriers. In order to determine the nature of interaction between nitric oxide and carrier, the carrier was heated after nitric oxide absorption at 60° C. for four hours. Practically no loss of weight was observed, which indicated that the nitric oxide gas reacted chemically with the carriers (entries 1-4 in Table 1).

In order to investigate the reactivity of 1,3-propanediol with nitric oxide, nitric oxide absorption was studied using (a) HNC 157-69, which did not contain 1,3-propanediol, and (b) 1,3-propanediol by itself HNC 157-69 gained 0.95 g or 0.56% weight, much lower compared to its 1,3-propanediol containing analog HNC 157-62, which showed 1.69% weight gain (entries 2 and 5 of Table 1). 1,3-propanediol itself, surprisingly, showed only negligible, if any, weight gain when NO was passed through it (entry 6 in Table 1). Thus, under experimental conditions, 1,3-propanediol did not react with nitric oxide.

Two samples were also prepared containing 800 ppm NO (from carrier HNC 157-62) and one sample containing 500 ppm NO (from carrier HNC 157-65) (entries 7-9 in Table 1). The IR spectra of the carriers did not show any additional bands after the reaction, possibly because of low amounts of nitrites and/or overlap with the carrier complex bands.

Mass spectral studies of the carrier HNC 157-62 and HNC 157-62 containing NO indicated that there was an increase in the intensity of the peak at m/e 104 in NO-containing carrier, compared to carrier without NO. The peak at m/e 104 was believed to be due to choline cation (C₅H₁₄NO). Phospholipon-90G may contain some free choline, and hence presence of the peak at 104 in the mass spectrum of the carrier was not surprising. However, the increase in the amount of choline after passage of NO was somewhat unexpected, although it is believed that nitric oxide catalyzes similar dephosphorylation of Phospholipon-90G releasing choline.

In conclusion, an increase in weight (0.56 to 1.69%) was observed when nitric oxide gas was passed through the carriers. 1,3-propanediol failed to gain any significant weight when nitric oxide was passed through it. HNC 157-69 (devoid of 1,3-propanediol) gained only 0.56% weight compared to 1.69% by its 1,3-propanediol containing analog HNC 157-62. The mass spectra of HNC 157-62 before and after passing NO indicated that the peak corresponding to choline at m/e 104 increased after the passage of NO, which suggests that phospholipon-90G may undergo NO-catalyzed dephosphorylation.

TABLE 1 Expt. Initial Final Time Temp. Wt. % Wt. No. Carrier wt. g. wt. g. hr ° C. Gain g gain 1 HNC 168.53 169.48 24 25 0.95 0.56 157-62 2 HNC 171.31 174.21 48 25 2.90 1.69 157-62 3 HNC 174.21* 174.01 4 60 −0.20 −0.11 157-62 4 HNC 171.66 172.98 24 25 1.32 0.77 157-65 5 HNC 171.02 171.97 40 25 0.95 0.56 157-69 6 1,3- 178.81 178.97 40 25 0.16 0.09 Propane- diol 7 HNC 238.16 238.35 2 25 0.19 0.0798 157-62 (~800 ppm) 8 HNC 250.37 250.50 2 25 0.13 0.0519 157-65 (~500 ppm) 9 HNC 252.24 252.45 0.25 25 0.21 0.0833 157-62 (~800 ppm)

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.

In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03. 

What is claimed is:
 1. A composition for transdermal delivery of nitric oxide, comprising: an emulsion comprising a first phase comprising molecular nitric oxide and lecithin, and a second phase comprising an emulsifier, wherein the lecithin is present at at least about 0.25% by weight of the composition, wherein the molecular nitric oxide is present at at least about 0.5% by weight of the composition and the molecular nitric oxide is present within the emulsion as a gas or bound by hydrogen bonds or van der Waals forces to the lecithin, and wherein the first phase comprises no more than about 250 ppm of water by weight of the composition.
 2. The composition of claim 1, wherein the first phase forms discrete vesicles contained within the second phase.
 3. The composition of claim 2, wherein the first phase forms liposomes contained within the second phase.
 4. The composition of claim 1, wherein the nitric oxide is present at at least about 0.5% by weight of the composition.
 5. The composition of claim 1, wherein the lecithin is present at at least about 0.5% by weight.
 6. The composition of claim 1, wherein the lecithin comprises a phosphatidylcholine.
 7. The composition of claim 6, wherein at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising a stearic diglyceride linked to a choline ester of a phosphoric acid.
 8. The composition of claim 6, wherein at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising a palmitic diglyceride linked to a choline ester of a phosphoric acid.
 9. The composition of claim 6, wherein at least some of the phosphatidylcholine comprises a phosphatidylcholine comprising an oleic diglyceride linked to a choline ester of a phosphoric acid.
 10. The composition of claim 6, wherein at least some of the phosphatidylcholine comprises a polyenylphosphatidylcholine.
 11. The composition of claim 10, wherein the polyenylphosphatidylcholine comprises linoleic acid.
 12. The composition of claim 10, wherein the polyenylphosphatidylcholine comprises dilinoleoylphosphatidylcholine.
 13. The composition of claim 1, wherein the composition is a gel.
 14. The composition of claim 1, wherein the composition is a cream.
 15. The composition of claim 1, wherein the composition is substantially transparent.
 16. A method of formulating a topical nitric oxide composition, the method comprising: mixing a polyglycol and a phosphatidylcholine to form a phosphatidylcholine solution; and delivering gaseous molecular nitric oxide into the phosphatidylcholine solution.
 17. The method of claim 16, wherein the phosphatidylcholine solution further comprises a siloxylated polyether.
 18. The method of claim 16, wherein the phosphatidylcholine solution further polydimethylsiloxane.
 19. The method of claim 16, further comprising adding methyl paraben to the phosphatidylcholine solution.
 20. The method of claim 16, comprising bubbling the nitric oxide into the phosphatidylcholine solution. 